Clearance valve assembly



Oct. 20, 1931. c. s. BAKER 1,827,725

CLEARANCE VALVE ASSEMBLY Filed Oct. 12, 1929 IN V EN TOR. Charles S.Baker Hfj' ATTORNEY Patented Oct. 20, 1931 UNITED STATES- PATENT OFFICEamiss s. Ben n, or contains, NEW Your, 'AssIsNon r0 INGERSOLL-RAND com-1.2mm, or am CITY, NEW JERSEY. A conroRArroN or New JERSEY cLEAn'A vcnvALvE n'ssnmntv Application filed 0ctober12, 1929. Serial as. 399,242.

This invention relates to compressors, but

a more particularly to a clearance valve assembly for machines of thistype.

The/objects of the invention are to obtain 5 an eflicientclearanceivalveand to adequately cushion the-valveby means of pressure fluid forpreventing a sharp impact of the valve against theelements which act asstops therefore. 7 b Other objects will be in part obvious and in partpointed out hereinafter.

4 The figure in the accompanying drawing is. asectional elevation ofaclearance valve assembly constructed in accordance with the V '15practice of the invention and showing it applied toa clearancepocket ofa compressor.

Referring more particularly to the drawing, -representsthe head of acompressor ofthe type having-two spaced walls, such as a 3'. the walls,B and C, to form therebetween a clearance pocket orchamber D which maycommunicate with the compressor throng an aperture E in the wall C. p v

Formed coaxially with the aperture E and 3 in'the wall B is athreadedaperture F'to accommodate a'threaded' flange G of a valve guide Thevalve guide H in this instance comprises anouter. member J and an innermember K which lies withintheouter mem- 1 3 her J and has an integralflange L wherein are formed apertures 10 to accommodate bolts P wherebytheinner member K may be secured to the outer memberJ; e a Both membersJ and K are provided with bores,v that: in the member J being designated.byQ. and the bore in the member K being designated by R. The bore R isof somewhat smaller diameter than thebore Q. and is the accommodation ofa head r mmed by a pl Z which extends through the extension and tliemember K and has a threaded projecting end I) to receive a nut 0 wherebythe In is secured firmly in position, The head thus forms a fixed headfor the chamber X, and at the innermost end of the chamber is anactuating area (1 against which pressure fluid mayact to retract thevalve.

The head Y is preferably of sufiiciently smaller diameter than thediameter of the chamber X so that upon each stroke of the compressorpiston aportion of compressed fluid may flow into the chamber X ortherefrom, depending upon the direction in which the compressor pistonismoving. o In order to prevent a too free flow of pressure fluid betweenthe head Y and the wall of the chamber X iston rings 6 may be disposedin the head to fit loosely in the chamber X so that pressure fluid mayenter into and flow from the chamber X during the compression andsuction strokes of the piston.

The rearward or freeend of the extension S of the valve in this instanceconstitutes a pressure surface 7 against which pressure uid may act forclosing the valve T and for holding it in the closed position during thetime the compressor is operating under full load. Such pressure fluidmay be introduced irito tie bore R through a passage 9 in the P 11g IThe pressure fluid used for'this purpose may lie-conveyed to the passage9 by a pipe h threaded into the nut c and which may lead from a suitablesource of supply preferably from the storage receiver (not shown) intowhich the compressor discharges.-

Suitable controlling devices (not shown) may be interposed in the pipe hto automatically introduce pressure fluid into the bore R to hold thevalve T upon the seat V during such times that the storage pressure isbelow the maximum value which it is intended to maintain and toautomatically exhaust the pressure fiuid from the bore R 'whenever themaximum pressure in the storage receiver is reached so that the valve Tmay then open to provide clearance for the compressor cylinder and thusreduce the discharge output to the storage receiver.

the enlarged portion adjacent the extension S to seat against acorresponding bevelled seat 73 on the member K. Ports 0 are formedintheskirt ofthe guide member J adjacent the bevelled seatjc .to assure.the exposure of the bevelled surface jto the samefpr'essure to which theseating portion-isexposed in" the unseated position of' the valve.

pressure surface f are of equal areas it follows that the opposedsurfaces ofthe enlarged portion W'of the valve, such) as the seatingportion U and the bevelled surface jv are also of equal areas. Due tothis fact the movement of the valve will. in no wise be affected; byvariations in the pressure fluid in the clearance chamber D which itcontrols. Only, those pressures acting against the pressure surface 7,and the pressure area at will effect the actuation of the valve T whichtherefore "reciprocates without fluttering 'or without impacting withforce against. its seats, q j v The operation of'thedevice is asfollows: Let 'it be assumed that the compressor to which the clearancevalveis appliedis operp ating'under normal condi'tions and that thepressure i'n the storage yreceilver into which the compressor discharges1 s somewhatbelow the maximum predetermined pressure which itis'intended to be maintained therein.

, Undertheseconditionspressure fluid will be admitted by suitable.c'ont'rolling devices (not shown) through the pipe h, the passage ginto the bore R to act against the actuf atmg surface .7 of the valveforholding the valve firmly seated againstthe seat V in the Wall ThevalveT will be thus held closed by pressure fluid duringthertime'thecompressor is operating to build up the prede; termined receiver.pressure.

' Upon each compressionstrokeof the compressor, piston pressure fluidwi'llfthen flow into the chamber Xbetween the cooperating surfaces ofthehead and the valve. Even though thepressuresu rfacef 'and thepressure area (Z are of substantially equal areas,

the valve will remain closed u'naflectedby thepressure fluid inthepressure chamber. Th1s1s dueto the fact thatupon the suction stroke ofthe c'ompressor'piston a portion of the pressure fluid previously forcedintothe 'chamber'X will again flow therefrom so that thereis a constantinduction and eduction of p ressure'flui'd into and from thephambeihX.however, a mean effective pressure will exist .in thechamber-X which,while of insuflicient forceto unseat the valve during the pres'ence ;-ofthepres sure fluid in the bore R. will, upon the exhaust of pressurefluid from the bOI'GR,

fluid within the chamber X.

ber. H 7

storage pressure has dropped below the maximum values, pressure fluidwill be admitted Inasmuch that the pressure area d and the by the icontrolling [dQVlCGS (not shown) through the pipe it into the bore R toreturn the valve T to its seat and the compressor will thereafteroperate atfullload. This movement of the valve will be a gradualmovement as it 'wil be to some extent retarded by the pressure fluid inthe chamber X and 53 the valve will therefore approach its seat withoutsharply imp acting thereagainstsince it is adequately cushioned by thepressure Iclaim: I i

1. A clearance valve assembly, comprising a valve guidehaving a bore, avalve in the bore having a chamber, means forintroduc ing-pressure fluidinto the bore tofclose-the valve, and means in the valve and stationarywith respect to for controlling the admission and exhaust of fluid intoand from the chamber to cushion the movement ofthe valve.

2; A clearance'valve assembly, comprising a valve guide having a bore, avalve-in the C19 bore having a chamber, means for introducing pressurefluidpinto' the bore to close the valve, and .means'in constantengagement with the valve for restricting the opening of the chamber forcontrollingthe admission 5105 and exhaust of fluid into and from thechamber to cushion the movement ofthe valve.

3. A clearancevalve assembly, comprising a valve guide having a bore, avalve in the bore having a chamber, means for introduc- 61 ing pressurefluid into the bore for closing the valve, and means in constantengagement with the valve to define the 'outlet'opening of .the chamberfor controlling the flow of cushioning fluid into and from the chamber.3115 4. A clearance valve assembly, comprlsing a valve guide having abore, a valve in the bore having a chamber, means for introducingpressure fluid into the bore f or closing the valve, a plug extendingthrough the valve. and a head on the ,plug lying in the chamber and inconstant engagement with the wall thereof to define the :outlet openingof the chamber ,forjcontrolling the 'flow of cushioning fluid into andfrom the char in 5. A clearance valve assembly, comprising a valve guidehavinga difierentialbore,a jvalvein the bore having a chamber, o apressure surface on the valve, means for introduc- Q.

' 'ing pressure fluid into the bore to act against the pressure surfacefor closing the valve, a ressure area in the chamber of substantialy thesame area as the pressure surface, a plug extending through the valve,and a head on the plug lying in the chamber in constant engagement withthe valve to define the outlet opening thereof for controlling the flowgt cushioning fluid into and from the cham- In testimony whereof I havesigned this specification.

CHARLES S. BAKER.

